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Triticeae Genomics and Genetics 2012, Vol.3, No.4, 38-43
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Figure 4 Sequence alignment between the obtained fragment of
Kr
gene and S-locus receptor kinase gene
2 Discussions
DNA sequence of the
Kr
gene wheat has not been
reported so far. Only 14 expression sequence tag (EST)
and a cDNA sequence of
Kr
gene in wheat could be
retrieved in GenBank, which seemed no overlapping
and unknown nucleotides by detection in DNAstar
software with the trimmed optimization of 14 ESTs,
and furthermore these sequences could not carry out
the sequence assembly used for a template designing
primer.
Therefore, in this research, the only cDNA sequence
(GenBank accession No.: AB379558.1) was employed
to design primers. However the primer designed based
cDNA sequences applied to amplified genomic DNA
that might result in leaping over the RNA splice sites
of primers due to the presence of the intron as well as
being difficult to specifically match the template
resulting in amplification failure. This would be one
of the reasons why only three of the six chosen
materials yielded target products.
Obviously, the activity of the
Kr
gene exhibited
differences in distant hybridization system, The
pollination between wheat and rye was more difficult
than the of wheat and maize, which indicated that the
diversity of the
Kr
genes and the complexity of the
Kr
gene expression should be existence. Although the
Kr
gene sequence obtained in the three genotypes shared
high homology in this research, we failed to obtain the
Kr
gene in another three genotypes. So we speculated
that there would be more plenty polymorphisms of
Kr
gene sequence happening in large testing samples.
Studies have shown that self-incompatibility S locus
(S-locus) is the multiple alleles encoding S locus
receptor kinase (SRK) (Stein et al, 1991), S-locus
glycoprotein (SLG) (Nou et al., 1993) and S-locus
cysteine-rich protein (SCR) (Schopfer et al., 1999),
wherein, SCR is signaling molecules of self-incom-
patibility (SI), specifically expressed in pollen that
plays the role of ligand; SLG and SRK express in the
pistil mastoid where SRK is the recognition factor for
SI signal.in the stigma acting as the receptor but SLG
act as assistant receptor. Interaction caused by pollen
ligand receptor and stigmatic papillae cells results in
SI signal transduction in the stigma papillae, even-
tually leading to the reaction of self-incom- patibility
(Takayama and Isogai, 2005; Fujimoto and Nishio,
2007; Zhang et al., 2010). In this research the obtained
Kr
gene fragment shared 85% homology with wheat S
locus receptor kinase gene within the same region,
which would provide an insight to further understand
the function of the
Kr
gene in wheat.
3 Materials and Methods
3.1 Experimental materials
Six genotypes were chosen from the 285 Chinese
wheat mini-core germplasms as the experimental
materials according to the report of Qi etc. (1997) and
our previous results of the hybridization between
wheat and corn (Cai et al., 2006; 2007), the selected
germplasms were Mazhamai, Xiaobaimang, Tokesun-
yihao, Chinese Spring, Yangmai, and Zhengmai9023,
The seeds germinated one week at 25
℃
, young leaves
were picked to extract genomic DNA.
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